The consciousness puzzle

Humans are aware, and we are aware that we're aware. But scientists still don't understand why.

April 02, 2006|David P. Barash | David P. Barash is professor of psychology at the University of Washington and tries to be conscious, at least part of the time.

CONSCIOUSNESS has long been the third rail of biology: touch it and maybe you don't die, but you are unlikely to get anywhere. Recently, however, the neurobiology of consciousness has become one of the hottest areas of research, along with genomics and stem cells.

For centuries, philosophers pondered consciousness, although no one really expected them to come up with anything. Descartes' renowned cogito, for example, was modified thusly by Ambrose Bierce: cogito cogito ergo cogito sum -- "I think I think, therefore I think I am," to which Bierce added that this was about as close to truth as philosophy is likely to get! But now we have microelectrodes recording from individual nerve cells, computers modeling neural nets, functional MRIs and even newer 21st century techniques hot on the trail of how consciousness emerges from "mere" matter.

Meanwhile, there is another side of bona fide consciousness research that has received all too little attention: Why consciousness exists in the first place. Evolutionary biologists find it useful to divide questions into two basic groups: essentially "how" and "why." So even as the how of consciousness is being revealed, little progress has been made on why.

Let's stipulate that consciousness is characterized by a curious recursiveness in which individuals are not only aware but aware that they are aware, in which case the "why" question is: "Why are we able to think about our thinking, instead of just plain thinking?" Isn't it enough to feel without also feeling good -- or bad -- about the fact that we are feeling?

It is quite possible to imagine a world inhabited by highly intelligent zombies, who go about their days responding appropriately to stimuli but lacking consciousness. Computers can play winning chess and perform difficult calculations, but they don't show any signs of possessing an independent or even rebellious self-awareness, like HAL in "2001: A Space Odyssey."

Moreover, there are downsides to consciousness, such as the pain of reflecting on one's inevitable death, or the paralysis of excessive self-consciousness, which makes us liable to trip over ourselves, whether literally -- attempting to perform some physical act done best when in an athlete's unreflective "zone" -- or cognitively, because of the infamous, chattering "monkey mind" that disturbs our inner peace.

Biologically, consciousness seems hard to justify, if only because it evidently requires a large number of nerve cells, the elaboration and maintenance of which is bound to be energetically expensive. What is the compensating payoff?

One possibility -- a biological "null hypothesis" -- is that maybe consciousness hasn't been an evolutionary development at all; maybe it is a non-adaptive byproduct of having large brains. A single molecule of water, for example, isn't wet. Neither are two, or, presumably, a few thousand, or even 1 million. But enough of them result in wetness -- not because wetness is adaptively favored over, say, dryness or bumpiness, but simply as an unavoidable physical consequence of piling up enough H2O molecules.

Can consciousness be like that? Accumulate enough neurons -- perhaps because they permit their possessor to integrate diverse inputs and generate complex responses -- wire them up and presto, consciousness?

Alternatively, maybe consciousness -- an unfolding story that we tell ourselves, moment by moment, about what we are doing, feeling and thinking -- really is adaptive, which is to say, it somehow benefited its possessors.

As to why, my favorite theory is that consciousness evolved as a kind of Machiavellian intelligence, improving our ability to interpret how others are likely to perceive us. Call it the Robert Burns benefit, from the last stanza of the Scottish poet's celebrated meditation: "O wad some Pow'r the giftie gie us/To see oursels as others see us!/It wad frae monie a blunder free us/An' foolish notion."

If, as sometimes suggested, character is what we do when no one is looking, maybe consciousness is precisely a Burnsian evolutionary gift, our anticipation of how we seem to others who are looking. And maybe it evolved, accordingly, in the service of our highly developed social intelligence, insofar as it helped free us from many a blunder and foolish notion by enabling our consciously endowed ancestors to realize (in proportion to their consciousness) that, for example, seeming too selfish, too cowardly, too uninformed, too ambitious, too sexually voracious and so forth would ill serve their ends.

The more aware our ancestors were, according to this argument, the more able they were to modify others' impressions of them, and hence, their own evolutionary success. If so, then genes "for" consciousness would have enjoyed an advantage over alternative genes "for" obtuseness.

As for the ultimate "why" of consciousness? For now, no one knows. (At least, not consciously.)